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Crabb E, Aggarwal A, Stephens R, Shao-Horn Y, Leverick G, Grossman JC. Electrolyte Dependence of Li + Transport Mechanisms in Small Molecule Solvents from Classical Molecular Dynamics. J Phys Chem B 2024; 128:3427-3441. [PMID: 38551621 DOI: 10.1021/acs.jpcb.3c07999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
As demands on Li-ion battery performance increase, the need for electrolytes with high ionic conductivity and a high Li+ transference number (tLi) becomes crucial to boost power density. Unfortunately, tLi in liquid electrolytes is typically <0.5 due to Li+ migrating via a vehicular mechanism, whereby Li+ diffuses along with its solvation shell, making its diffusivity slower than the counteranion. Designing liquid electrolytes where the Li+ ion diffuses independently of its solvation shell is of significant interest to enhance the transference number. In this work, we elucidate how the properties of the solvent influence the Li+ transport mechanism. Using classical molecular dynamics simulations, we find that a vehicular mechanism can be increasingly preferred with a decreasing solvent viscosity and increasing interaction energy between the solvent and Li+. Thus, a weaker interaction energy can enhance tLi through a solvent-exchange mechanism, ultimately improving Li-ion battery performance. Finally, metadynamics simulations show that in electrolytes where a solvent-exchange mechanism is preferable, the energy barrier to changing the coordination environment of Li+ is much lower than in electrolytes where a vehicular mechanism dominates.
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Affiliation(s)
- Emily Crabb
- Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, Massachusetts 02139, United States
- Physics Program, Centre College, 600 W Walnut St, Danville, Kentucky 40422, United States
| | - Abhishek Aggarwal
- Research Laboratory of Electronics, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, Massachusetts 02139, United States
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, Massachusetts 02139, United States
| | - Ryan Stephens
- Shell International Exploration & Production Inc., Houston, Texas 77082, United States
| | - Yang Shao-Horn
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, Massachusetts 02139, United States
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, Massachusetts 02139, United States
| | - Graham Leverick
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, Massachusetts 02139, United States
| | - Jeffrey C Grossman
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, Massachusetts 02139, United States
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Fang C, Yu X, Chakraborty S, Balsara NP, Wang R. Molecular Origin of High Cation Transference in Mixtures of Poly(pentyl malonate) and Lithium Salt. ACS Macro Lett 2023; 12:612-618. [PMID: 37083344 DOI: 10.1021/acsmacrolett.3c00041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
The rational development of new electrolytes for lithium batteries rests on the molecular-level understanding of ion transport. We use molecular dynamics simulations to study the differences between a recently developed promising polymer electrolyte based on poly(pentyl malonate) (PPM) and the well-established poly(ethylene oxide) (PEO) electrolyte; LiTFSI is the salt used in both electrolytes. Cation transference is calculated by tracking the correlated motion of different species. The PEO solvation cage primarily contains 1 chain, resulting in strong correlations between Li+ and the polymer. In contrast, the PPM solvation cage contains multiple chains, resulting in weak correlations between Li+ and the polymer. This difference results in a high cation transference in PPM relative to PEO. Our comparative study suggests possible designs of polymer electrolytes with ion transport properties better than both PPM and PEO. The solvation cage of such a hypothetical polymer electrolyte is proposed based on insights from our simulations.
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Affiliation(s)
- Chao Fang
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States of America
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States of America
| | - Xiaopeng Yu
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States of America
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States of America
| | - Saheli Chakraborty
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States of America
- Energy Storage and Distributed Resources Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States of America
| | - Nitash P Balsara
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States of America
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States of America
| | - Rui Wang
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States of America
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States of America
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Sundararaman S, Halat DM, Reimer JA, Balsara NP, Prendergast D. Understanding the Impact of Multi-Chain Ion Coordination in Poly(ether-Acetal) Electrolytes. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c01897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Siddharth Sundararaman
- Joint Center for Energy Storage Research, the Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - David M. Halat
- Joint Center for Energy Storage Research, Department of Chemical and Biomolecular Engineering and College of Chemistry, University of California, Berkeley, California94720, United States
- Joint Center for Energy Storage Research, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Jeffrey A. Reimer
- Joint Center for Energy Storage Research, Department of Chemical and Biomolecular Engineering and College of Chemistry, University of California, Berkeley, California94720, United States
- Joint Center for Energy Storage Research, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Nitash P. Balsara
- Joint Center for Energy Storage Research, Department of Chemical and Biomolecular Engineering and College of Chemistry, University of California, Berkeley, California94720, United States
- Joint Center for Energy Storage Research, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - David Prendergast
- Joint Center for Energy Storage Research, the Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
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